"To detect the momentum of a photon, one actually detects the momentum of an interacting particle of mass. Photons as such are not directly detectable. Indeed, the photon is not just a "massless particle" and no one really understands just what it is." [See Richard Kidd, James Ardini, and Anatol Anton, Evolution of the Modern Photon, American Journal of Physics, 57(1), Jan. 1989, p. 27-35.]

This term historically was first applied to indivisible amounts of electromagnetic, or light, energy usually referred to as photons. The photon, or quantum of the electromagnetic field, is a massless particle, best interpreted as such by quantizing Maxwell's equations. [McGraw-Hill Concise Encyclopedia of Science & Technology]

(foton) , the particle composing light and other forms of electromagnetic radiation, sometimes called lightquantum. The photon has no charge and no mass. About the beginning of the 20th cent., the classical theory that light is emitted and absorbed by matter in a continuous stream came under criticism because it led to incorrect predictions about several effects, notably the radiation of light by incandescent bodies (see black body) and the photoelectric effect. These effects can be explained only by assuming that the energy is transferred in discrete packets, or photons, the energy of each photon being equal to the frequency of the light multiplied by Planck's Constant, h. Because the value of Planck's constant is extremely small (6.62 ? 10 27 erg sec.), the discrete nature of light energy is not evident in most optical phenomena. The light imparts energy and momentum to a charged particle when one of the photons collides with it, as is demonstrated by the Compton effect. (source not known)
Photon

Boson : An integral spin particle to which Bose-Einstien statistics apply. Such particles do not follow the Pauli exclusion principle. Photons, pions, alpha particles, and nuclei of even mass numbers are examples of bosons. FermiLab

The carrier particle of the electromagnetic interaction. Depending on its frequency (and therefore its energy) photons can have different names such as visible light, X rays and gamma rays. We describe light in several ways. When we talk about "photons" we generally think of uncharged particles with out mass that carry energy (but be careful, there are other particles like this!). Photons of light are known by other names too, such as gamma rays and x-rays. Low-energy forms are called ultraviolet rays, infrared rays, even radio waves! A photon is one of the fundamental particles in nature and it plays an important role involving electron interactions. Photons are the most familiar particles in everyday existence. The light we see, the radiant heat we feel, microwaves we cook with, are make use of photons of different energies. An x-ray is simply a name given to the most energetic of these particles.

PHOTON (foton) , the particle composing light and other forms of electromagnetic radiation, sometimes called light quantum. The photon has no charge and no mass. About the beginning of the 20th cent., the classical theory that light is emitted and absorbed by matter in a continuous stream came under criticism because it led to incorrect predictions about several effects, notably the radiation of light by incandescent bodies (see black body) and the photoelectric effect . These effects can be explained only by assuming that the energy is transferred in discrete packets, or photons, the energy of each photon being equal to the frequency of the light multiplied by Planck's constant, h. Because the value of Planck's constant is extremely small (6.62 ? 10 27 erg sec.), the discrete nature of light energy is not evident in most optical phenomena. The light imparts energy and momentum to a charged particle when one of the photons collides with it, as is demonstrated by the Compton Effect. See quantum theory. Photon is a quantum of electromagnetic radiation; an elementary particle that is its own antiparticle.

Boson An integral spin particle to which Bose-Einstien statistics apply. Such particles do not follow the Pauli exclusion principle. Photons, pions, alpha particles, and nuclei of even mass numbers are examples of bosons. FermiLab

Boson - any particle that obeys Bose-Einstein statistics but not the Pauli exclusion principle; all nuclei with an even mass number are bosons
even spin bosons - mediate attractive forces
gauge boson - a particle that mediates the interaction of two elementary particles
gluon - a gauge boson that mediates strong interaction among quarks
graviton - a gauge boson that mediates the (extremely weak) gravitational interactions between particles
intermediate vector bosons - a gauge boson that mediates weak interactions between particles
Odd spin bosons - mediate repulsive forces
neutral Z bosons - constitute a "neutral current"
photon - a quantum of electromagnetic radiation; an elementary particle that is its own antiparticle

Fermions

Fermions are subatomic particles such as protons, neutrons, and electrons that have half-integer spins (1/2, 3/2, etc) and atoms comprised of odd numbers of the particles such as three. Electrons are fermions.

Unlike bosons, another form of elementary particle that have integer spins (1, 2, 3, etc), identical fermions are prevented by the laws of quantum physics from sharing the same state of being. For example, identical fermions cannot share the same location or momentum. But photons, which are bosons, can - which is why lasers work.

Two fermions that bind strongly into a molecule become a boson because their spins add to an integer value but, in the Colorado experiment, the fermions did not link that tightly. However, they behaved enough like bosons to allow them to share the same momentum for about one ten-thousandth of a second.

Low-temperature superconductors carry current via pairs of electrons that are bound weakly at distances of about a thousand times the usual distance between electrons.